I've tried both, and I think that helmet mounted definitely lights the way better - and you can "flash" drivers to let them know you are there (just don't put the light in their eyes too long blinded drivers = bad!) Look where you want to light and voila its lit. You can avoid blinding other cyclists (or drivers) just by looking down or away. That said I still have my light mounted on my handlebars... the cord for the battery is short and it was just too awkward to have the battery up on my helmet too. I think I can probably get and extension and keep the battery in my pocket, which I should do someday....